Over the past few years, byproduct gypsum from electric utility flue gas desulfurization (FGD) systems has replaced natural gypsum in many of the gypsum wallboard plants across North America. Installation of FGD scrubbers will continue into the future because of new environmental rules. This will result in more high quality gypsum being produced and disposed of each year. Environmental agencies have set goals for utilization of coal combustion products such as FGD gypsum rather than landfill. This paper illustrates the supply/demand imbalance that will develop using current usage patterns, as well as highlight the future trends and new technologies that could bring this into balance. Over the next 20 years the North American supply of byproduct gypsum is going to exceed the demand by a wide margin, with a surplus of 10 - 15 million tons per year by 2015. This byproduct gypsum should not be considered a low value waste product, like wet sand. There are several high volume applications that could use this material and take advantage of its inherent chemical properties. The economics are such that both producer and consumer could benefit from this approach, with our natural environment being the ultimate benefactor. One of the most promising high volume applications is the low cost production of alpha hemihydrate/gypsum cement. Alpha hemihydrate is a high strength gypsum plaster that sells for USD250 -USD800 per ton depending on the quality and the application. There are numerous recent patents/papers that cover the manufacture of alpha gypsum with the likelihood that the incremental cost to produce this material could be USD35 -USD50 per ton. This would open up many new markets for this high performance material and bring the demand of this byproduct gypsum into balance with supply. Other end uses that are expected to be economically viable are fertilizers and fillers.
展开▼
